Light emitting device and manufacturing method thereof

ABSTRACT

Disclosed are a light emitting device and a method for manufacturing the same. The light emitting device includes a substrate having a lead frame, a light emitting diode mounted on the substrate, a mold member formed on the substrate and the light emitting diode, and a reflecting member having an opening portion at one side thereof and being inclined at an outer portion of the mold member.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a 371 of PCT/KR2007/000547 filed on Feb. 1, 2007,which claims priority to KR patent application 10-2006-0014092 filed onFeb. 14, 2006.

TECHNICAL FIELD

The embodiment of the present invention relates to a light emittingdevice and a method for manufacturing the same.

BACKGROUND ART

Light emitting diodes (LEDs) constitute a light emitting source by usingGaAs, AlGaAs, GaN, InGaN, and InGaAlP-based compound semiconductormaterials, thereby realizing various colors. Such LEDs have been appliedto various fields such as a lightening indicator, a character indicator,and an image indicator using colors.

In general, characteristics of the LEDs are determined depending onmaterials, colors, brightness, and the range of brightness intensity ofa compound semiconductor, and mainly affected by a package structure ofmounting an LED chip.

FIG. 1 is a sectional view showing a related art light emitting device.

Referring to FIG. 1, a reflecting cup 20 is fabricated through aninjection molding process using white plastics, and lead frames 11,which are electrically insulated from each other, are formed in a cavityof the reflecting cup 20. The lead frame 11 is provided with an LED chipelectrically bonded thereto by a wire. Both end portions of the leadframes 11 pass through the reflecting cup 20 such that the end portionsare used as electrode terminals.

The cavity of the reflecting cup 20 is filled with a mold part 40including transparent epoxy resin. The mold part 40 includes a yellowfluorescent substance such as YAG:Ce fluorescent substance. The yellowfluorescent substance absorbs blue light emitted from a blue LED chip 30and is excited by means of the blue light, so that yellow light can beemitted. The yellow light is mixed with the blue light so that whitelight is emitted. Accordingly, a white LED can be realized.

In this case, the reflecting cup 20 has a length in the range of about 2mm to 4 mm, a width in the range of about 0.4 mm to 2 mm, and a heightin the range of about 0.6 mm to 2 mm.

In such a light emitting device, the lead frame 11 is arranged in thecavity of the reflecting cup 20, and the LED chip 30 is mounted on thelead frame 11. However, the blue LED chip 30 cannot easily be mounteddue to the space limitation of the cavity of the reflecting cup 20.Accordingly, the productivity of the light emitting device may decrease,and the defect rate of the light emitting device may increase.

In addition, since the mold part 40 having the fluorescent substancecannot be easily inserted into the reflecting cup 20 due to the narrowcavity of the reflecting cup 20, the color reproduction and the lightefficiency of white light emitted from a side light emission type LEDmay be degraded.

DISCLOSURE Technical Problem

An embodiment of the present invention provides a side-emission typelight emitting device.

An embodiment of the present invention provides a light emitting deviceand a method for manufacturing the same, capable of guiding lightemitted from a light emitting diode to an opening portion formed at oneside of the light emitting device by forming a reflecting memberupwardly inclined toward the opening portion on a substrate.

Technical Solution

An embodiment of the present invention provides a light emitting devicecomprising a substrate including lead frames, a light emitting diode onthe substrate, a mold member on the substrate and the light emittingdiode, and a reflecting member including an opening portion at one sidethereof and being inclined at an outer portion of the mold member.

An embodiment of the present invention provides a method formanufacturing a light emitting device, the method comprising the stepsof mounting a light emitting diode on at least one of lead frames of asubstrate, forming a mold member on the light emitting diode and thesubstrate, and forming a reflecting member, which is inclined toward anopening portion formed at one side thereof, around the mold member.

Advantageous Effects

In a light emitting device and a method for manufacturing the sameaccording to embodiments of the present invention, a reflecting memberhaving an inclined structure is additionally provided over a lightemitting diode, thereby easily mounting the light emitting diode andmolding a mold member. Accordingly, the yield rate of the light emittingdevice can be improved.

In addition, heat generated from the inside of the light emitting devicecan be effectively dissipated by using the reflecting member so that thedegradation of efficiency of the light emitting diode caused by the heatcan be prevented.

DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view showing a related art light emitting device;

FIG. 2 is an exploded perspective view of a light emitting deviceaccording to a first embodiment of the present invention;

FIG. 3 is a side sectional view showing a light emitting deviceaccording to a first embodiment of the present invention;

FIG. 4 is a front view showing a light emitting device according to afirst embodiment of the present invention;

FIG. 5 is a side sectional view showing a light emitting deviceaccording to a second embodiment of the present invention;

FIG. 6 is a front view showing a light emitting device according to athird embodiment of the present invention;

FIG. 7 is a front view showing a light emitting device according to afourth embodiment of the present invention; and

FIG. 8 is a front view showing a light emitting device according to afifth embodiment of the present invention.

BEST MODE

Hereinafter, a light emitting device according to embodiments of thepresent invention will be described with reference to accompanyingdrawings.

It will be understood that when an element is referred to as being “on”or “under” a layer, it can be directly on/under the layer, and one ormore intervening layers may also be present. FIGS. 2 to 4 show a lightemitting device 100 according to a first embodiment of the presentinvention. FIG. 2 is an exploded perspective view of the light emittingdevice 100, FIG. 3 is a side sectional view showing the light emittingdevice 100, and FIG. 4 is a front view showing the light emitting device100. Referring to FIGS. 2 to 4, the light emitting device 100 includes asubstrate 110, a light emitting diode 120, a mold member 130, and areflecting member 140.

The substrate 110 includes a sapphire substrate, an FR-4 substrate, or aPCB. In addition, the substrate 110 is provided with a plurality of leadframes 112 electrically insulated from each other. The lead frames 112extend along at least a portion of a top surface, a side surface, and abottom surface of the substrate 110 such that the lead frames are usedas electrode terminals 114 at a lower portion of the substrate 110. Inthis case, the substrate 110 may be realized as a support memberincluding non-conductive materials such as plastics.

In addition, the lead frames 112 include metals such as Ag or Al havinga high reflection coefficient, and the surfaces of the lead frames 112may be coated with the materials having the high reflection coefficient.

The light emitting diode 120 is bonded on the lead frames 112 by usingconductive or non-conductive adhesion and electrically connected to thelead frames 112 by using a wire 122 in the shape of a LED chip. Thelight emitting diode 120 is mounted through a wire bonding scheme, a diebonding scheme, or a flip-chip bonding scheme according to the type ofthe LED chip, such as a vertical LED chip or a horizontal LED chip, andthe mounting scheme for the LED chip.

At least one light emitting diode 120 may be mounted on the substrate.The light emitting diode 120 includes at least one of LED chips usingAlGaN, InGaN, GaN, InGaAlP, AlGaAs, and GaAs-based compoundsemiconductor materials. For example, all three-color (red/green/blue)LED chips or only at least one blue LED chip may be mounted on thesubstrate 110. According to the embodiment, since space limitation doesnot exist when the light emitting diode 120 is mounted on the substrate110, the light emitting diode 120 can be easily mounted on the substrate110. In addition, a protection device such as a zener diode may bemounted on the substrate 110.

The mold member 130 is formed on the substrate 110 while being inclinedwith respect to the top surface of the substrate 100. The mold member130 seals the light emitting diode 120 and electrical connection partsthereof by using transparent epoxy or silicon resin.

The mold member 130 may be formed through a transfer molding schemeusing epoxy molding compound (EMC). According to the transfer moldingscheme, the substrate 110 is arranged on a molding press equipped with amold having a desired shape, and the EMC is injected into the mold at apredetermined pressure or more, thereby transfer-molding the mold member130. In this case, the epoxy resin may be selected by taking intoaccount a characteristic of easily sticking to the substrate 110 or thelead frames 112 together with high light transmittance and low stress.

In addition, a fluorescent substance may be added to the mold member 130or not depending on types of the light emitting diode 120. For example,when three-color (Red, Green, and Blue) LED chips are mounted, whitelight can be emitted by using the three-color LED chips. For thisreason, a fluorescent substance need not be added to the mold member130. Further, when only a blue LED chip is mounted, a yellow fluorescentsubstance is added to the mold member 130 such that white light can beemitted. In addition, when an ultraviolet (UV) LED chip is mounted, red,green, and blue fluorescent substance may be added to the mold member130.

In order to add a fluorescent substance to the mold member 130, afluorescent pigment, which is excited in reaction with light generatedfrom the light emitting diode 120, is mixed with mold compound epoxy,and then the mixture is molded with the mold member 130 through thetransfer molding scheme. The fluorescent substance includes a YAG:Ce orsilicate based yellow fluorescent substance. Thus, the light generatedfrom the blue LED chip is mixed with yellow light emitted from theyellow fluorescent substance, so that white light is realized.

The top surface of the mold member 130 is inclined relative to thesubstrate 110. In other words, the mold member 130 is upwardly inclinedtoward an opening portion at one side of the reflecting member 140(e.g., □). In this case, as shown in FIG. 3, the top surface of the moldmember 130 is inclined at an angle in the range of 15° to 85° from thesubstrate 110. Such a mold member 130 has a longitudinal length in therange of about 3.5 mm to 5 mm, a transverse length in the range of about1 mm to 2 mm, and the maximum height in the range of about 1 mm to 2.5mm. At least one surface (e.g., top surface) of the mold member 130according to the present invention can be inclined or bent in amulti-step structure. The mold member 130 may have an externalappearance of a semi-circular shape, a polygonal shape or an embossshape.

Further, the mold member 130 according to the embodiment may be moldedthrough a molding scheme of heat-pressing an epoxy sheet, a thermalscheme of heat-treating liquid-phase molding materials, or aninjection-molding scheme, as well as the transfer molding scheme.

The reflecting member 140 is formed on the mold member 130. Thereflecting member 140 has an opening portion at one side thereof, andthe top surface 142 and both side surfaces 144 of the reflecting member140, except for the opening portion, cover the mold member 130.

Such a reflecting member 140 has a shape and an inclination anglecorresponding to those of the mold member 130. The top surface 142 ofthe reflecting member 140 is downwardly inclined from a front endportion 145 to a rear end portion 146, and is inclined toward theopening portion. Accordingly, light generated from the light emittingdiode 120 may be directly emitted to the opening portion while passingthrough the mold member 130. In addition, the light may be reflectedfrom the reflecting member 140 such that the light is emitted.

Such a reflecting member 140 may be formed with a shape the same as theexternal shape of the mold member 130, and the top surface 142 of thereflecting member 140 may be inclined with an angle identical to ordifferent from that of the top surface of the mold member 130.

The reflecting member 140 may be formed by using materials having a highreflection coefficient or/and a low light absorption coefficient. Indetail, the reflecting member 140 is coated with metals such as Al, Ag,and Au or oxide-based materials having a high reflection coefficient.For example, the Ag has a high reflection coefficient in the range of96% to 98% or more. The reflecting member 140 may formed by depositingmetals having a high reflection coefficient thereon through metaldeposition, metal coating, electrolytic plating, or electroless plating.

In addition, an insulating member 135 may be formed on the lead frame112 corresponding to the reflecting member 140. The insulating member135 includes an insulating tape or non-conductive adhesion or gluingagent including epoxy. In addition, the insulating member 135 is formedbetween the lead frame 112 and the reflecting member 140 so that thereflecting member 140 is electrically insulated from the lead frame 112.

Meanwhile, according to a procedure of manufacturing the light emittingdevice, the light emitting diodes 120 are adhered to N×M chip mountingareas (N and M are natural numbers exceeding 1) and then bonded to thelead frames 112 of the substrate 110 by using a wire. Then, the moldmember 123 including epoxy resin or silicon resin is molded and cured onthe chip mounting areas of the substrate 110. At this time, the topsurface of the mold member 130 is inclined at a predetermined angle.

Then, the reflecting member 140 including metal material having a highreflection coefficient is formed on the surface of the mold member 130.After forming the reflecting member 140, a sawing process is performedin a package unit of the light emitting device so that the individualdiode packages are prepared. At this time, since one side of the moldmember 130 is cut, the opening portion of the reflecting member 140 isformed. Hereinafter, the operational procedure of the light emittingdevice will be described.

As shown in FIGS. 2 and 4, the light emitting diode 120 mounted on thesubstrate 110 receives current through the lead frames 112 so as to emitlight. A portion of the emitted light passes through the mold member 130so that the portion of the light is directly emitted to the openingportion at one side of the reflecting member 140. Remaining portions ofthe emitted light are reflected from the top surface and side surfacesof the reflecting member 140 positioned at the upper portion and bothside portions of the light emitting diode 120 and then guided to theopening portion. At this time, light incident to the lead frame 112 isreflected again.

When white light is realized by using a blue LED chip and a fluorescentsubstance, a portion of light passing through the mold member 130 isexcited by a yellow fluorescent substance added to the mold member 130so that yellow light is emitted. Thus, the yellow light of the yellowfluorescent substance is mixed with blue light emitted from the bluelight emitting diode 120 so that the white light is emitted.

In addition, when white light is realized by using three-color (red,green, and blue) LED chips, lights generated from the LED chips passthrough the transparent mold member, are reflected by the reflectingmember, and then emitted to the opening portion of the reflectingmember. At this time, the thee-color lights are mixed with each other atthe outside/inside of the mold member and then realized as the whitelight.

FIG. 5 is a side sectional view showing a light emitting deviceaccording to a second embodiment of the present invention.

As shown in FIG. 5, a light emitting diode 220 is mounted on at leastone of lead frames 214 of a substrate 210, and a mold member 230 havingan inclined structure is molded on the light emitting diode 220. Whenthe mold member 230 is molded, the rear surface of the mold member 230is formed at a right angle such that the rear surface 244 of areflecting member 240 formed over the mold member 230 can be formed at aright angle or an angle in the range of 60 degrees to 120 degrees. Inthis case, an insulating member 235 electrically insulates thereflecting member 240 from a lead frame 212.

A top surface 242 and the rear surface 244 of the reflecting member 240reflect light generated from the light emitting diode 220 to an openingportion at one side of the reflecting member 240.

FIG. 6 is a front view showing a light emitting device according to athird embodiment of the present invention.

As shown in FIG. 6, a reflecting member 340 has an external appearanceof a semi-circular shape identical to that of a mold member 330. Thesemi-circular reflecting member 340 is inclined similarly to thestructure shown in FIGS. 3 and 5. In addition, the reflecting member 340is electrically insulated from a lead frame 312 by an insulating member335.

In such a light emitting device, light generated from a light emittingdiode 320 mounted on at least one of the lead frame 312 of a substrate310 is reflected toward an opening portion due to the semi-circularinclination structure of the light reflecting member 340.

FIG. 7 is a front view showing a light emitting device according to afourth embodiment of the present invention. As shown in FIG. 7, anexternal appearance of a reflecting member 440 has a polygonal shapecorresponding to that of a mold member 430. The polygonal reflectingmember 440 is inclined similarly to the structure shown in FIGS. 3 and5. In addition, the reflecting member 440 is electrically insulated froma lead frame 412 by an insulating member 435.

In such a light emitting device, light generated from a light emittingdiode 420 mounted on at least one of the lead frames 412 of a substrate410 is reflected toward an opening portion by a polygonal inclinationstructure of the reflecting member 440. FIG. 8 is a front view showing alight emitting device according to a fifth embodiment of the presentinvention. As shown in FIG. 8, an external shape of a reflecting member540 is formed with a structure in which a top surface 542 of thereflecting member 540 is plane, and both side surfaces thereof arecurved corresponding to that of a mold member 530. The top surface 542of the reflecting member 540 is inclined similarly to the structureshown in FIGS. 3 and 5.

In such a light emitting device, light generated from a light emittingdiode 520 mounted on at least one of the lead frame 512 of a substrate510 is reflected toward an opening portion by an inclination structureof the reflecting member 540.

In another modified structure according to the present invention, bothside surfaces of a reflecting member as well as a top surface thereofmay be inclined. In other words, the interval between both sides of thereflecting member becomes narrowed toward a rear end portion from afront end portion of the reflecting member. Accordingly, the top surfaceand both side surfaces of the reflecting member are upwardly inclinedtoward an opening with respect to light incident on a light emittingdiode so that external light efficiency can be increased.

A light emitting device according to the present invention is a sidelight emission type LED package, and the height and the inclinationangle of a mold member are adjusted according to products so that thesize of the package can be changed. Accordingly, an orientation angleand optical power can be improved.

Accordingly, although embodiments of the present invention are describedin detail, it must be noted that the embodiments are for the purpose ofonly description, but not the limitation thereof. In addition, thoseskilled in the art will appreciate that various modifications, additionsand substitutions are possible, without departing from the scope andspirit of the invention.

INDUSTRIAL APPLICABILITY

In a light emitting device and a method for manufacturing the sameaccording to embodiments of the present invention, a reflecting memberhaving an inclination structure is additionally formed over a lightemitting diode, thereby easily installing a light emitting diode andmolding a mold member and improving the production yield rate of thelight emitting device. In addition, since heat can be effectivelydissipated by using a reflecting member, the degradation of efficiencyof the light emitting diode caused by the heat can be prevented.

1. A light emitting device, comprising: a substrate including aplurality of electrodes; a light emitting diode on the substrate andelectrically connected to the plurality of electrodes; a mold member onthe substrate and the light emitting diode; a reflecting member formedon the mold member; and an insulating member disposed among thereflecting member and the plurality of electrodes, wherein thereflecting member includes a metal material.
 2. The light emittingdevice as claimed in claim 1, wherein the mold member includes epoxyresin or silicon resin.
 3. The light emitting device as claimed in claim1, wherein the mold member comprises a fluorescent substance absorbing aportion of light emitted from the light emitting diode so as to change awavelength of the light emitting diode.
 4. The light emitting device asclaimed in claim 1, wherein the reflecting member is inclined toward anopening portion at an angle in a range of 15° to 85° relative to thesubstrate.
 5. The light emitting device as claimed in claim 1, whereinthe reflecting member includes oxide-based reflection metal or metalincluding one of Al or Ag.
 6. The light emitting device as claimed inclaim 1, wherein the reflecting member has one of a polygonal shape, asemi-circular shape, or a circular-planar shape.
 7. The light emittingdevice as claimed in claim 1, wherein the insulating member includesnon-conductive adhesion or non-conductive gluing agent.
 8. The lightemitting device as claimed in claim 1, wherein the light emitting diodeincludes at least one light emitting diode chip including one selectedfrom the group consisting of AlGaN-based, InGaN-based, GaN-based,InGaAlP-based, AlGaAs-based, and GaAs-based compound semiconductormaterials on the substrate.
 9. The light emitting device as claimed inclaim 1, wherein at least one side surface of the reflecting member isinclined at an angle in a range of 60° to 120° from the substrate. 10.The light emitting device as claimed in claim 1, wherein the lightemitting diode is bonded to the plurality of electrodes of the substratethrough a wire-bonding scheme or a flip chip-bonding scheme.
 11. Thelight emitting device as claimed in claim 1, wherein the plurality ofelectrodes extend along at least a portion of a top surface, a sidesurface, and a portion of a bottom surface of the substrate.
 12. Thelight emitting device as claimed in claim 1, wherein the plurality ofelectrodes include Ag or Al.
 13. The light emitting device as claimed inclaim 1, comprising a zener diode on the substrate.
 14. The lightemitting device as claimed in claim 1, wherein the mold member has asurface which has one of a semi-circular shape, a polygonal shape or anemboss shape.
 15. The light emitting device as claimed in claim 1,wherein the reflecting member includes an opening portion.
 16. The lightemitting device as claimed in claim 1, wherein the reflecting member islocated on at least one side surface of the mold member.
 17. A lightemitting device, comprising: a substrate including a plurality ofelectrodes; a light emitting diode on the substrate and electricallyconnected to the plurality of electrodes; a mold member on the substrateand the light emitting diode; a reflecting member formed on the moldmember; and an insulating member disposed among the reflecting memberand the plurality of electrodes, wherein the reflecting member includesa metal material and is inclined with respect to a top surface of thesubstrate.
 18. The light emitting device as claimed in claim 17, whereinthe reflecting member includes an opening portion, and wherein thereflecting member is located on at least one side surface of the moldmember except for the opening portion.
 19. The light emitting device asclaimed in claim 17, wherein an opening portion of the reflecting memberis formed at a side surface of the mold member.
 20. The light emittingdevice as claimed in claim 17, wherein an upper surface of the moldmember is inclined at an angle of 15° to 85° from a top surface of thesubstrate.
 21. A light emitting device, comprising: a substrateincluding a plurality of electrodes; a light emitting diode on thesubstrate and electrically connected to the plurality of electrodes; amold member on the substrate and the light emitting diode; and areflecting member formed on the mold member and including an openingportion, wherein the reflecting member includes a metal material havingat least one of Al or Ag.
 22. The light emitting device as claimed inclaim 21, further comprising: an insulating member formed on theplurality of electrodes and disposed around a periphery of the moldmember, wherein the reflecting member is formed on the insulatingmember.